Photocatalyzed CO2 reduction

A mixed system using [Co(HMD)] (27, HMD = 5,7,7,12,14,14-hexamethyl-1,4,8, ll-tetraazacyclotetradeca-4,11-diene) as a catalyst instead of 26 also photocatalyzes CO2 reduction. The reaction mechanism of this system has been investigated in detail by Fujita et al. [44], One-electron reduction of 27 by TP produces [Co (HMD)] . An adduct between [Co (HMD)] and CO2 produces CO, while a iP" adduct gives HCOOH and H2 (Scheme 6). 

Monoclinic crystals of BiV04 photocatalyzed CO2 reduction to C2H5OH in aqueous solution without a sacrificial electron drmor [84]. BiV04 can act as visible-light responsive photocatalyst, and photocatalytic activity improved under intense light irradiation. The maximum TF reached ca. 1.5 nunol (g cat.) h. The authors presumed that the intense irradiation enhances the production of reactirm intermediates. 

Reduction of carbon dioxide and its intermediates is catalyzed by illumination. Photocatalyzed reduction of CO2 to formaldehyde and methanol has been observed on semiconductor powders suspended in solution (25) as well as on GaAs electrodes (26). 

Lichtin NN, Vijayakumar KM. (1983). Photocatalyzed Light-Driven Reduction of Co2 and N2 on Semiconductor Surfaces. JElectrochem Soc. 130, C108-C. 

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